Optical Hazard Alarm Smoke Dust Steam Signal Evaluation
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Solution Overview
Problem
Existing optical hazard alarms face challenges in distinguishing between smoke and dust/steam particles, leading to potential false fire alarms and reduced sensitivity, as they often suppress one signal to enhance the other, which can be influenced by manufacturing tolerances and environmental factors.
Innovation Solution
The method involves irradiating particles with both infrared and blue light, normalizing the scattered light signals to coincide for larger particles, and transforming them into polar coordinates to generate separate smoke and dust/steam density signals, allowing for independent evaluation and processing, with progressive and degressive weighting based on polar angles to maintain sensitivity and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If only the second scattered light signal with blue light wavelength is evaluated to increase sensitivity for smoke particles, then smoke detection sensitivity is improved, but false alarms are triggered by dust particles
Solution Approach 1:
The evaluation of scattered light signals is segmented into two independent channels: one for smoke detection and one for dust/steam detection. Each channel processes the normalized scattered light signals separately to produce distinct density signals, allowing independent evaluation without mutual interference.
Solution Approach 2:
Normalized scattered light signals serve as intermediaries that are transformed into polar coordinates (polar angle and distance). These intermediate representations enable the system to differentiate between smoke and dust/steam characteristics before generating final density signals.
2Reliability
If the difference is formed between the second scattered light signal with blue light wavelength and the first scattered light signal with infrared light wavelength to suppress dust influence, then false alarms are suppressed, but sensitivity for smoke detection is reduced
Solution Approach 1:
The signal processing is segmented into separate evaluation paths: one path generates smoke density signals optimized for smoke detection, while another path generates dust/steam density signals optimized for dust detection. This segmentation allows each path to maintain its own sensitivity without being compromised by the other.
Solution Approach 2:
The system applies partial differentiation by using weighted combinations of scattered light signals rather than complete suppression. The weighting factors allow retention of useful signal components while suppressing unwanted influences, maintaining sensitivity without complete signal rejection.
3Loss of information
If two separate signals for smoke and dust/steam are output, then independent evaluation and additional safety information are provided, but signal processing complexity increases
Solution Approach 1:
The same normalized scattered light signals and polar coordinate transformation are used universally for both smoke and dust/steam detection. This multi-functional approach allows a single processing framework to generate multiple types of density signals without requiring separate independent processing systems.
Solution Approach 2:
The system changes parameters (weighting factors, polar angle ranges) to transform the same input signals into different output signals. By adjusting these parameters, the system can optimize for different detection goals while using the same underlying processing architecture.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables high sensitivity for smoke detection while maintaining low sensitivity for dust/steam, preventing false alarms and providing additional safety information on dust and steam densities, even under varying environmental conditions.
Implementation Method 1
an optical hazard alarm operating in accordance with the scattered light principle
Data Source
AI summary
A method evaluates two scattered-light signals in a hazard alarm operating in accordance with the scattered light principle. The particles to be detected are irradiated with light in a first wavelength range and with light in a second wavelength range. The light scattered by the particles is converted into a first and second non-normalized scattered light signal. The two scattered light signals are normalized in relation to one another such that their amplitude curve approximately coincides for larger particles such as dust and steam. The two normalized scattered light signals are transformed into a polar angle and a distance as polar coordinates of a polar coordinate system. Finally a respective smoke density signal and a respective dust/steam density signal is formed from a current distance value, wherein for this purpose the respective current distance values, depending on a current polar angle value, are weighted in opposition to one another.